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Tag: forests

Well, anyone who says that temperate countries could do with a little warming ought to read this study. Trees are dying at double the usual rate in the last 17 years.

Warmer temperatures have dramatically increased the rate at which trees in old-growth forests are dying in parts of British Columbia and the western United States, a study says.

The study, to be published in Friday's edition of the journal Science, found that mortality rates for trees in the old-growth plots in the Pacific Northwest — including parts of southern British Columbia — had doubled in 17 years.

Forests in California and other states had less dramatic numbers. The interior states — like Arizona, Colorado and Idaho — had tree mortality rates that doubled every 29 years. The mortality rates change incrementally every year, the researchers say.

“We may only be talking about an annual tree mortality rate changing from 1 per cent a year to 2 per cent a year, an extra tree here and there,” study author Mark Harmon, professor of forest ecology at Oregon State University, said in a statement.

“But over time a lot of small numbers can add up. The ultimate implications for our forests and environment are huge.”

The increases in mortality rates are replicated across all trees at every elevation, regardless of species or size.

The study, which the researchers say is the first of its kind on temperate forests, gathered data on 76 long-term forest plots over a 50-year period for analysis. All of the forest areas studied were at least 200 years old, although individual trees varied in age and size.

The study controlled for all other variables including the infamous pine beetle, and found that temperature increase was to blame. Why? A 1ºC rise in temperature results in less snow, longer summer and increased drought stress. The effects on any one individual tree would not be significant, but if you look at an entire population, these stresses caused a doubling of mortality.

Cutting forests is the third-largest source of climate-warming carbon emissions today, larger than the emissions produced by either the US or China. Including them in a "carbon market" is a tempting solution.

It comes down to this: Today, trees are worth more dead than alive. This despite the fact that they stash away billions of tons of carbon in their soil and themselves and constantly inhale more carbon from the atmosphere. They also help regulate the earth's climate in other ways, influencing rainfall patterns far away, including in the US. And they contain unique plant and animal life, the economic value of which is only beginning to be understood.

Yet no dollar figure is placed on these vital services. Instead, tropical forests are cut down in favor of enterprises such as palm oil plantations or cattle grazing, endeavours that make money here and now. It’s easy to see why rain forests continue to disappear at an alarming rate.

A report to the British government this month suggests that the way to recognize the true value of forests is by including them in carbon markets. Polluters around the world could earn credits to offset their own carbon emissions by paying for forest preservation.

A carbon sink needs to be valued as much as a carbon source. Making this really happen is of course very difficult, needing accurate forest cover mappings (now available), and strict enforcement in countries that may be hard to monitor.

The moral hazard of giving people money to do “nothing” of course is something conservatives will not like, but the trees are not doing “nothing”. Paying people for stewardship is not wrong. There would be an opportunity to change an extractive subsistence based economy into a service economy, with sustainable tourism, shade grown coffee, local guards and forest officers, etc.

I like this idea very much. Carbon offset markets have gotten a bad name recently, but a larger scale program is necessary.